Method of controlling plant pests with an iodine adduct of a copolymer of nu-vinyl pyrrolidone and a polymerizable vinyl compound containing one aliphatic double bond



United States Patent METHOD OF CONTROLLING PLANT PESTS WITH AN IODINEADDUCT OF A COPOLYMER OF N-VTNYL PYRROLIDONE AND A POLYMERIZ- ABLE VINYLCOMPOUND CONTAINING ONE ALIPHATIC DOUBLE BOND Jesse Werner, Holliswood,N. Y., and Frederick A. Hessel, Upper Montclair, and Daniel B. Witwer,.Montclair, N. 1., assignors to General Aniline & Film Corporation, NewYork, N. Y., a corporation of Delaware No Drawing. Application September19, 1955 Serial No. 535,263

5 Claims. (Cl. 16733) The present invention relates to a method ofprotecting plant material subject to attack by plant pests, and,particularly, to a method of controlling insects, fungi, foliar and soilnematodes.

Various organic compounds are currently employed in the control anderadication of agricultural and floricultural pests. Aldrin(1,2,3,4,10,10-hexachloro-1,4,4a,5,8,8a-hexahydro-l,4,5,8-dimethanonaphthalene) and Dieldrin(1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-1,4,5,8-dimethanonaphthalene) are highly toxic products,and insecticidal formulations containing them must be handled withextreme care. Parathion (0,0-diethyl-o-p-nitrophenylthiophosphate) is aremarkably eifective insecticide, and has been put to use on farms andgreenhouses to control many kinds of destructive insects infestingvarious crops. Because of its extreme toxicity to warm blooded animals,this potent insecticide cannot be used to control insects affecting manand animals.

All of the foregoing organic insecticides, including DDT[l,1,l-trichloro-2,2-bis (p-chlorophenyl) ethane], Chlordane,tetraethylpyrophosphate, and the like, are water insoluble, but solublein most of the currently employed organic solvents.

Insecticides differ in degree of toxicity. Man can tolerate pyrethrumand sulfur in rather large quantities, but small amounts of any one ofthe foregoing compounds would be dangerous. Special care must beobserved in applying sprays or dusts containing the foregoinginsecticides, especially to avoid breathing the dust or vapor of spraymist, and to avoid skin contact. Under conditions where large amounts ofsprays or dusts are applied, the operator must wear a respiratortogether with waterproof or protective clothing that will cover allexposed skin surfaces.

Fumigants differ from insecticides in that the fumes must be confined sothat the insect or pest is exposed to a considerable concentration forsome time. Organic phosphate insecticides such as,hexaethyltetraphosphate (HETP), tetraethylpyrophosphate (TEPP),tetraethyldipyrophosphate, parathion and other organic materials suchas, lindane, have been employed as aerosols in greenhouses to give acombined attack and fumigating effect. The vapors of these materials aretoxic to insects in extremely low concentrations. For soil fumigationethylene dibromide has been found to be an efiicient and economicalfumigant. It is a heavy liquid with a rather low rate of evaporation,and moves slowly through the soil. Liquid mixtures of dichloropropaneand dichloropropylene which are much lighter than ethylene dibromidehave been employed as soil fumigants, but the mixture is not nearly sotoxic to soil insects.

The main disadvantage of the methods employed in soil fumigation is thecost of the equipment needed to treat large seed beds and the amount oftime and labor involved in movingthe equipment such as, injectors,

broadcasters, etc. from place to place. With most fumigants a water sealmust be applied immediately for best results. The treated area must becovered with burlap sacks, canvas, and the like, which in turn must besprinkled with water and then removed after four or five days. planteduntil every trace of the fumigant has disappeared, which usually takesfrom 8-12 days. In wet, cool weather, it may take longer.

Chloropicrin forms a gas that is extremely toxic to plants in both thesoil and the air. Under certain weather conditions a blanket of gas maycollect over a fumigated bed near the ground, then drift slowly over anearby area, and cause severe injury to the plants growing there,especially at night when foliage is wet with dew.

D-D which is a mixture of 1,3-dichloropropylene and 1,2-dichloropropaneobtained as a by-product in the manuf acture of allyl alcohol frompetroleum is inflammable and is dangerous to use in enclosed space inthe presence of sparks or open flames. It is. dangerous to humans.Prolonged breathing of its vapors may cause the symptoms associated withthe inhalation of the vapors of chlorinated hydrocarbons. It is verydangerous if spilled on the skin, shoes or clothing, and is likely tocause irritation, a burning sensation, and blistering. Such mixture isapt to cause injury to plants, and is, therefore, used almost entirelybefore planting. I

Ethylene dibromide, which is a colorless liquid with a sharpchloroform-like odor, is highly toxic to humans,

since it is absorbed through the skin. It is also toxic to many plants,and soils treated with it should be aired thoroughly before planting.

Practically all of the presently available soil fumigants are toxic toplants, and for this reason the manufacturers strongly urge andrecommend that they be diffused out of the soil before a crop isplanted, otherwise the plants may be stunted. The time required foradequate aeration of the soil varies greatly, and is influenced by manyfactors, including the kind of soil, the condition of the soil, and thefumigant used together with other factors.

In addition to the aforementioned fumigants, formaldehyde, Lindane(mixture of benzenehexachloride isomers) and Parathion are alsoeffective for treating soil to destroy insects in greenhouses and plantnurseries where plants are growing. Small amounts of these materials areadded to soil 'in the greenhouse bench to control symphilids. The efiectis a combination of attack and fumigation. All of the currently usedsoil fumigants with the exception of formaldehyde and to some extentchloropicrin are water insoluble. They must be employed either inemulsion form or dissolved in a suitable organic solvent.

It is an object of the present invention to provide a method ofprotecting plant material subject to attack by insects, fungi andnematodes by treating said material with an iodine complex of acopolymer of N-vinyl pyrrolidone and polymerizable vinyl compoundcontaining one aliphatic double bond.

A further object is to provide a method of controlling soil pesticidesby applying to said soil a pesticidal amount of an iodine complex of acopolymer of N-vinyl pyrrolidone and polymerizable Vinyl compoundcontaining one aliphatic bond.

A still further object is to provide a method of applying a pesticidalamount of an iodine complex of copolymer of N-vinyl pyrrolidone andpolymerizable vinyl compound containing one aliphatic double bond toloci to be protected against fungi, insects and nematodes.

A still further object is a process of fumigating soil and eradicatingsuch nematodes from such soil and-thereby restraining them fromattacking the plants.

The soil is then allowed to aerate, and no seeds Other objects andadvantages willbecome apparent from the following description.

We have discovered that iodine complexes, i. e., iodine adducts, 'ofcopolymers of N-vinyl pyrrolido'ne and a vinyl-compound containing onealiphatic double linkage are very stable compositions, soluble in water,and are extremely effective in the control of plant insects, plant fungiand' soil organisms." The iodine complexes employed in accordance withthe present invention have no toxic effect as such, or the effect ofresidue thereof on plants or warm blooded animals including man.

In copending application of William-M. Perry, Serial No. 535,262 filedon even date, there is disclosed a novel iodine complex of copolymers ofN-vinyl pyrrolidone and a nitrogen-free polymerizable vinyl compoundwhich have been found to be ofsubstantial value for many applications inwhich advantage is taken of the bactericidal and fungicidal activity ofiodine, and in which the irritating and sensitizing properties of theiodine are substantially overcome. In order to obtain complete waterso1ubility of the iodine complex, or iodine adduct, it is essential thatthe copolymer contain 60-90% by weight of a N-vinyl pyrrolidone and40-10% by weight of any polymerizable nitrogen-free vinyl compoundcontaining one aliphatic double bond.

All of the iodine complexes disclosed in the said application are usefulin achieving the foregoing objects.

Further details regarding the copolymeric iodine complexes or iodineadducts utilized in accordance with the present invention may beobtained by reference to the aforementioned pending application, thecontents of which are incorporated herein by reference, especially thevarious copolymeric iodine complex compositions as prepared inaccordance with Examples I to X inclusive.

In addition to the various copolymeric iodine complexes disclosed in theaforementioned pending application, including Examples 1 to X inclusive,we may also employ iodine complexes" of copolymers of N-vinylpyrrolidone and nitrogen bearing vinyl compounds, such as, for example,acrylamide, vinyl phhtalamide, and a vinyl pyridine characterized by thefollowing general formula:

wherein A is selected from the group consisting of hydrogen, methyl,ethyl, vinyl and a-methylvinyl groups, at ,7

least one and not more than two of said As being of the group consistingof vinyl and a-methylvinyl groups.

As specific illustrations of such vinyl pyridines, the following may bementioned:

odsknown in the art by simply copolymerizing the two copolymericmaterials in the aforestated concentrations. The method ofcopolymerization may be either in bulk, in emulsion, or in solutionwhile employing an organic solvent, such as, benzene, dioxane, acetone,methyl ethyl ketone, ethylene chloride or mixtures thereof. The solutionof the two monomers, i. e. a vinyl pyrrolidone and either an acrylamide,vinyl phthalamide, or a vinyl pyridine in the aforestated concentrationsis heated in the usual manner in the presence of a polymerizingcatalyst, such as, bcnzyl peroxide, lauroyl peroxide,a,o-azodiisobutyronitrile, and the like.

The percent by weight of the reactive monomers to be employed inpreparing the copolymers of N-vinyl pyrrolidone and nitrogen-freepolymerizable vinyl compound may be the same as stated in theaforementioned application of William M. Perry, where complete watersolubility is desired, or the copolymer may contain 30 by weight of aN-vinyl pyrrolidone and 70-20% by weight of any polymerizablenitrogen-free vinyl compound containing one aliphatic double bond. Inthe latter case, although complete water solubility is not attained, thecopolymer-especially the iodine complexthereof-is sufficiently solubleto form aqueous solutions containing 1 to 3% by weight of thecopolymeric iodine adduct.

When copolymerizing a nitrogen bearing vinyl compound of the'typedisclosed herein with a N-vinyl pyrrolidone, the percent by weight ofthe reactive monomers to be employed may be arranged so as to give acopolymer containing 1090% by weight of N-vinyl' pyrrolidone and -10% byweight of any nitrogen hearing polymeriza'ble vinyl compound. As theN-vinyl pyrrolidone content increases up to 65% by Weight and higher thecopolymer and the iodine adduct thereof is sufiiciently soluble to yieldaqueous solutions containing from 0.1 to 2.5% by weight of thecopolymeric iodine adduct. In the event the N-vinyl pyrrolidone contentin the copolymer ranges from 10 to 60% by weight, the iodine complex ofsuch copolymer is only slightly soluble in water. In such case thecopolymer iodine complex is mixed with a solid carrier such as talc,etc, containing from 1 to 10% by weight of the complex and applied as adust composition directly to plants and soil.

In preparing the iodine complex, elemental iodine and the powderedcopolymer are mixed until a homogeneous powder is obtained, the mixingbeing carried out by grinding the iodine and copolymer in a mortar andpestle, or in a suitable mechanical mixer such as a ball millconstructed of such materials which are not attacked by iodine.Thereafter the homogeneous mixture is heated for a period of timeranging from 1 to several hours, i. e. anywhere from 2 to 24 hours at atemperature ranging between 90-120 C. The time of mixing varies onlywith the efficiency thereof, as the combination of the copolymer withiodine on its surface is rapid, in fact, such combination will occur tosome extent by dropping the iodine crystals on the dry powderedcopolymer.

On completion of the mixing, there is obtained a compound in a physicalstate similar to the copolymer alone but which contains varyingproportions of iodine available (as distinguished from free iodine),iodide ion, and bound iodine. A distinction between these forms may bemade on an analytical basis, available iodine being determined directlyby dissolving a sample of the product in water and titrating with 0.1-Nsodium thiosulfate solution using starch as an indicator. The amount ofiodine present asiodide ion is determined by reducing the iodinecompound in solution with l-N sodium acid sulfite, adding enough to makethe solution colorless, then adding 0.1-N silver nitrate and enoughnitric acid to make the solution acidic and back-titrating with ammoniumthiocyanate. The iodide ion is the difference between this figure andthe available iodine asdetermined above. The total iodine may bedetermined by I combustion methods such as that formulated by Hallett inScotts Standard Method of Chemical Analysis, bound iodine then beingdetermined by subtracting the sum of available iodine and iodide ionfrom the total iodine as determined above.

The iodine complex or adduct thus obtained has an available iodinecontent ranging from 0.1 to 25% by weight of the copolymer. With anygiven sample of copolymer, the iodine present as available iodine andiodide ion may vary somewhat. Further details regarding the formation ofthe iodine complex may be obtained by reference to U. S. P. 2,706,701 ofHans Beller and W. A. Hosrner, issued on April 19, 1955, the contents ofwhich are incorporated herein by reference.

As noted above, it is not absolutely essential that the copolymer iodinecomplex have complete water solubility since, if the product ispartially or negligibly soluble, a suflicient concentration forpesticidal control can be made by dispersing it in aqueous medium bymeans of any one of the commercially available surface active agents.Moreover, such compounds can be applied as mixtures with a solidcarrier, such as clay, talc and the like, as will be pointed outhereinafter.

The copolymeric iodine complexes utilized in accordance with the presentinvention form aqueous solutions, dispersions and dusts having highpesticidal activity. Aqueous solutions or dispersions of thecompositions may be employed as such in the form of sprays orin comtionto proceed over a longer period, and provide for the retention of toxicconcentrations of the composition in soil for extended periods. Thecomposition will kill a number of insect species, but will not injuregrowing plants and aeration is not necessary before planting.

(3) In aqueous concentrations, even as high as 20% by weight, thecopolymeric iodine adduct (containing as much as' 25% available iodine)is not toxic to warm blooded animals, human beings, and plants ingeneral. If the material is accidentally spilled on skin or clothing,there will be no physiological effect, i. e., no injury to skin.

(4) Other unusual features and characteristics 'will become apparentfrom the following description:

Regardless of the concentration of the copolymeric iodine adduct,aqueous solutions and dispersions thereof have a tendency to adhere toleaves and stems, including inflorescence, and form a thin filmcontaining-the toxic ingredient. With repeated rain or spray hosing, thefilm is dissolved and washed away. The copolymeric iodine adduct is notonly useful as an insecticide, insectifuge, fungicide, but also againstvarious foliarand root nematodes, and a large variety of soil pests..For example, aqueous solutions containing 0.075 to approximately 5% byweight of the iodine-adduct, when applied directly to plants, controlvarious species of aphids, red spider mites, scales, etc. Dustcompositions, i. e. mixed with a solid carrier such as clay, talc, etc.containing from 1 to by weight of the iodine-adduct may be applieddirectly for insect andfungi control. Aqueous solutions, dispersions, ordust compositions containing from-0.1 to by weight of the copolymericiodine adduct having 1 to 15 of available iodine control leaf nematodes,Aphelenchoides ritzema-bosi; root knot nematodes, Meloidogyne species;leaf spot, Alternaria species, Septoria chrysanthemi andCyclindrosporium chr'ysanthemi.

Aqueous solutions containing from 100 to 1000 parts per million ofcopolymeric iodine adduct having 1 to 25% of available iodine are veryefficient'in'the control and eradication of'soil pests such as gardencentipedes, i. e. symphilids, Scutigerella immaculata, wire worms,white-fringed beetle, beetle grubs and various other soil pests andnematodes. t

It isto be .noted that the application of aqueous solutions ordispersions of the copolymeric iodine adduct does not require the costlyequipment as is the case with the currently used soil fumigants andnematocides. The costs which are very-high and the operations at timesdifficult are completely eliminated by the use of aqueous solutions ordispersions in accordance with the present invention. The aqueoussolution, which is preferred, is merely sprayed on the soil in theconcentration of 10- 20% by weight and hosed in with water or rain andallowed to soak in. A light application may be made'to the top of thesoil, and the soil rototilled so as to loosen it up and to make itporous, and a second application given. Hosing or rain will wash thetoxicant into the soil and kill the various insects with which it comesin ,contact. t

The copolymeric iodine adducts whether employed as statedconcentrations, have an extremely low phytocidal action. In other words,they are non-toxic to plants but highly toxic'to various insects, fungi,nematodes and soil pests. Instead of'employing the copolymeric iodineadduct in either solution or dust form, the compound may be dissolved ina small amount of acetone or alcohol or even with water, and the aqueoussolution emulsified with volatile liquid organic propellants, i. e.aerosols such as ethylene chloride, propylene chloride, or a mixture ofethylene chloride, carbon tetrachloride, etc.

The following examples will illustrate the manner in which thepesticidal compositions prepared in accordance with the aforementionedpending application and the disclosure hereof may be employed in thecontrol of destructive insects, fungi, nematodes, and the like.

, Exampl I 1 level teaspoonful, weighing approximately 3.3 grams,

of a copolymer of by weight of N-vinyl-2-pyrrolidone 10% by weight ofvinyl stearate containing 2.8% of available iodine was dissolved in onegallon of water. The solution was sprayed under and over all the leavesof Chrysanthemum morifolium including two basal leaves which wereinfected with the leaf nematode, Aphelenchoides ritzema-bosi. Afterthree days the infected basal leaves did not show a further spreading ofthe disease which is characterized by the development of brownwedge-shaped areas on foliage, usually starting at the base and workingupward. The infected leaves were removed. With about four sprayapplications, perfect control of leaf nematodes was achieved, i. e., atthe maturity date of the plant, it blossomed without showing anyindication of nematode injury in any of the remaining leaves.

.Exampl e II A potted geranium (Pelargonium) in which the soil wasinfected with symphilids, Scutigerella immaculata, was -wetted with anaqueous 0.5% solution of a copolymer of 90% by weight ofN-vinyl-2-pyrrolidone and 10% by weight of vinyl chloride containing1.4% of avail- The wetting was continued until the solution began toooze out at the bottom of the drain.

After 4 hours, the geranium plant was removed from the pot, and the soildumped into a white earthenware vessel and suflicient water added topartially submerge the soil. With the aid of a S-power magnifying lense,the surface of the water was observed with no activity in thesymphilids. They were scooped out and placed into a Petri dishcontaining .a thin layer of water, and the dish covered. After one hourthe total inactivity persisted, thus indicating that'a complete kill wasefifectuated of all the symphilids. The geranium plant was repotted inthe same soil, fed a liquidfertilizer. and grew in a normal healthymanner.

Example III An aqueous solution of a copolymer of 90% by weight a ofN-vinyl-2-pyrrolidone and by weight of vinyl stearate containing ofavailable iodine was prepared so that the concentration was 1000 ppm. 10pre-adult or young adult nematodes of the species Panag'rellusredivivuswere immersed in the solution, while an additional 10 nematodeswere placed in tap water as a control. Immediately a check was kept onthe time. After 15 min utes, minutes, 1' hour, 1 /2 hours, 2 hours andthereafter'at 2-hour intervals for a period of 24 hours the nematodeswere examined. The activity of the copolymeric iodine adduct was basedon the time required for total inactivation. During this test it wasfound that within two hours the specimens were-completely quiescent,

and five totally inactivated, i. e. became completely quiescent, andwere incapable of further motion. For practical purposes the completelyquiescent parasites can be considered as being dea'd. Between 2-4 hoursall nematodes were dead. The blank control showed motility of thenematodes at the end of the 4-hour' period.

The test was repeated with aqueous chloropicrin of the sameconcentration as a standard. A complete kill was obtained between 24hours, thus indicating that the copolymeric iodine adduct is equal tothe standard.

Example IV A 5% aqueous solution of a copolymer of 60% by weight of3-methyl-N-vinyl-Z-pyrrolidone and by weight of vinyl alcohol containing15% available iodine was applied by means of a small camel hair brush tothe dorsal thoracic region of 12 meal worm larvae, Tenebrio molizor.After 3 hours all the larvae were dead.

Example V 10 grams of a copolymer of 76% by weight of N-vinyl-2-pyrrolidone and 24% by weight of vinyl pyridine containing 12%available iodine and 5 grams. of sodium laurylsulphate were dissolved inwater and brought up to two gallons. When applied in the form of a sprayagainst red spider mites, Tetranychus binaculatus, gave a kill of 100%.The same spray applied to the aphids, Macrosiphum sanborni, gave a killof 98%.

Example VI One gallon of the solution of Example V was sprayed upon a 3X 2' flat of soil infected with damp ofi fungi, Fusarium spore. 'After ahosing with water to a depth of 8 inches, carnation seedlings wereplaced in the treated soil 6 inches apart. The seedlings grewvigorously, and no evidence of damping 0E was observed.

Example VII Example III was repeated with the exception that thecopolymer was replaced by a copolymer of 90% by Weight copolymericiodine adduct in which the percent of available. iodine ranges from.5-25%.

It is to be clearly understood that the copolymeric iodine adductprepared as above may be, applied undiluted or with a carrier such as asuspension in water or mixed with talc, clay or other currently usedcarriers.

We claim:

1. A method of protecting chlorophyllaceous plant material subject toattack by plant pests which comprises applying to said material apesticidal amount of an iodine complex of a copolymer of 10 to by weightof N- vinyl pyrrolidone and 9010% by weight of a polymerizable vinylcompound containing one aliphatic double bond, the available iodinecontent of said complex ranging from 0.1 to 25% by weight of saidcopolymer.

2. The method which comprises applying a pesticidal amount of an iodinecomplex copolymer containing from 0.1'to 25 by weight of availableiodine of said copolymer to loci of chlorophyllaceous plant material tobe protected against fungi, insects and nematodes, said iodine complexcopolymer containing 10 to 90% by weight of N- vinyl pyrrolidone and 90to 10% by weight of a polymerizable vinyl compound containing onealiphatic double bond.

3. A process of fumigating soil adaptable for the growing ofchlorophyllaceous plants which comprises introducing to said soil afumigating amount of iodine complex of a copolymer of 10 to 90% byweight of N-vinyl pyrrolidone and 9-10% by weight of a polymerizablevinyl compound containing one aliphatic double bond, the availableiodine content of said complex ranging from 0.1 to 25% by weight of saidcopolymer.

4. A process of eradicating nematodes from soils adaptable for thegrowing of chlorophyllaceous plants Which comprises introducing into thesoil in the vicinity of said nematodes a nematocidal amount of an iodinecomplex of a copolymer of 60 to 90% by weight of N- vinyl pyrrolidoneand 40 to 10% by weight of a polynierizable vinyl compound containingone aliphatic double bond, in which the available iodine content rangesfrom 0.1 to 25% by weight of said copolymer.

5. A method for controlling chlorophyllaceous plant insects and soilorganisms which comprises contacting said insects and organisms with aninsecticidal amount of an iodine complex of a copolymer of 60 to 90% byweight of N-vinyl pyrrolidone and 40 to 10% by weight of a polymerizablevinyl compound containing one aliphatic double bond, the availableiodine content of said complex ranging from 0.1 to 25 by weight of saidcopolymer.

References Cited in the file of this patent UNITED STATES PATENTS1,964,518 Karns June 26, 1934 2,237,567 Land Apr. 8, 1941 2,498,174Morris Feb. 21, 1950 2,534,285 Mahan Dec. 19, 1950 2,706,701 B'eller etal. Apr. 19, 1955 2,734,314 MacKay Feb. 14, 1956 2,739,922 ShelanskiMar. 27, 1956 2,742,736 MacKay Apr. 24, 1956 FOREIGN PATENTS 1,064,624France May 17, 1954 OTHER REFERENCES Am. Dyestufi Reporter, vol. 43, No.6, Mar. 15, 1954, p. 27. (Adv.)

Chem. Week, vol. 69, No. 25, Dec. 22, 1951, pp. 19-20.

ATES PATENT OFFICE UNITED ST COBBECTIO CERTIFICATE OF Patent No.2,853,417

September 23, 1958 Jesse Werner et el.

orreoted below It is harem! certi of the above numbered p uld read as cPatent sho 1116 29, for "9 is 13th dey of January 1959.

Column 8, 1 4.0%" read 90-10% Signed end sealed th (SEAL) Attest:

KARL ailment ROBERT c. WATSON Commissioner of Patents Atta ning Oificer

1. A METHOD OF PROTECTING CHLOROPHYLLACEOUS PLANT MATERIAL SUBJECT TOATTACK BY PLANT PESTS WHICH COMPRISES APPLYING TO SAID MATERIAL APESTICIDAL AMOUNT OF AN IODINE COMPLEX TO A COPOLYMER OF 10 TO 90% BYWEIGHT OF NVINYL PYROLLIDONE AND 90-10% BY WEIGHT OF A POLYMERIZABLEVINYL COMPOUND CONTAINING ONE ALIPHATIC DOUBLE BOND, THE AVAILABLEIODINE CONTENT OF SAID COMPLEX RANGING FROM 0.1 TO 25% BY WEIGHT OF SAIDCOPOLYMER.